Introduction

At
the
root of all the converging crises in today's world is the
issue of human overpopulation. Each of the global problems we
face today is
the result of too many
people using too much of our planet's finite, non-renewable resources
and filling its waste repositories of land, water and air to
overflowing. The true danger posed by our exploding
population is not our absolute numbers but the inability of our
environment to cope with so many of us doing what we do.

It is becoming clearer every day, as crises like global warming, water,
soil and food depletion, biodiversity loss and the degradation of our
oceans constantly worsen, that the human situation is not
sustainable. Bringing about a sustainable balance between
ourselves and the planet we depend on will require us, in very short
order, to reduce our population, our level of activity, or both.
One of the questions that comes up repeatedly in discussions of
population is, "What level of human population is sustainable?"
In this article I will give my analysis of that question, and offer a
look at the human road map from our current situation to that level.

As I have mentioned elsewhere,
the concepts of ecological science are the most effective tools
for understanding
this situation. The crucial concepts are sustainability, carrying
capacity and overshoot. Considered
together these can give us some clue as to what the true sustainable
population of the earth might be, as well as the trajectory between our
current numbers and the point of sustainability.

Sustainability

A
sustainable population is one that can survive over the long term
(thousands to tens of thousands of years) without either running out of
resources or damaging its
environmental niche (in our case the planet)
in the process. This means that our numbers and level of activity
must not generate more waste than natural processes can return to the
biosphere, that the wastes we do generate do not harm the biosphere,
and that most of the resources we use are either renewable through
natural processes or are entirely recycled if they are not
renewable. In addition a sustainable population must not grow
past the point where those natural limits are breached. Using
these criteria it is obvious that the current human population is not
sustainable.

Carrying
Capacity

In
order
to determine what a sustainable population level might be, we need to
understand the ecological concept ofcarrying capacity.
Carrying capacity is the population level of an organism that can be
sustained given the quantity of life supporting infrastructure
available to it. If the numbers of an organism are below the
carrying capacity of its environment, its birth rate will
increase. If the population exceeds the carrying capacity, the
death rate will increase until the population numbers are stable.
Carrying capacity can be increased by the discovery and
exploitation of new resources (such as metals, oil or fertile
uninhabited land) and it can be
decreased by resource exhaustion and waste buildup, for example
declining soil fertility and water pollution.

Note:
"Carrying capacity" used in
its
strict sense means the sustainable
level of population that can be supported. This implies that all the resources a population uses
are renewable within a meaningful time frame. An environment can
support a higher level of population for a shorter period of time if
some amount of non-renewable resources are used. If the level of
such finite resources in the environment is very high, the population
can continue at high
numbers for quite a long time. Though some ecologists may cringe,
I tend to think in terms of "sustainable carrying capacity" and
"temporary carrying capacity". In this article I just use the
single term "carrying capacity" to indicate the population level that
can be supported by the environment at any moment in time. While
not strictly correct, this does simplify and clarify the discussion.

An increase in the carrying capacity of an environment can
generally be
inferred from a rise in the population inhabiting it. The
stronger the rise, the more certain we can be that the carrying
capacity has expanded. In our case a
graph of world population makes it obvious that something has massively
increased the world's carrying capacity in the last 150 years.
During the first 1800 years of the Common Era, like the tens of
thousands of years before, the population rose very gradually as
humanity spread across the globe. Around 1800 this began to
change, and by 1900 the human population was rising dramatically:

Part of the early phase of this expansion was due to the
settlement of
the Americas, but the exploitation of this fertile land in
the 16th to 19th centuries would not seem to be enough on its own to
support
the population explosion we have experienced. After all, humans
had already spread to every corner of the globe by 1900. There
is something else at work here.

The
Role of Oil

That
something is oil. Oil first entered general use around 1900
when the global population was about 1.6 billion. Since then the
population has quadrupled. When we look at oil production
overlaid on the population growth curve we can see a very suggestive
correspondence:

However,
we have to ask whether this is merely a coincidental
match. A closer look at
the two curves from 1900 to the 2005 reinforces the impression of a
close correlation:

The Food Factor

Are
there
other factors besides oil that may have contributed to the growth of
the
Earth's carrying capacity?

The main one that is usually cited is the enormous world wide increase
in food
production created by the growth of industrial agribusiness.
There is
no question that it has caused a massive increase in both yields and
the absolute quantities of food being grown worldwide. While it
has been celebrated with the popular label "The Green Revolution",
there is
nothing terribly miraculous about the process. When you
open up that so-called revolution, you find at its heart our friend
petroleum

Here's
how it works. Industrial agriculture as practiced in the 20th and
21st centuries is supported by three legs: mechanization,
pesticides/fertilizers and genetic engineering. Of those three legs,
the first two are directly dependent on petroleum to run the machines
and natural gas to act as the chemical feedstock. The genetic
engineering
component of agribusiness generally pursues four goals: drought
resistance, insect resistance,
pesticide resistance and yield enhancement. Meeting that last goal
invariably
requires mechanical irrigation, which again depends on oil.

Even more than other oil-driven sectors of the global economy, food
production is showing signs of strain as it struggles to maintain
productivity in the face of rising population, flattening oil
production and the depletion of essential resources such as soil
fertility and fresh water. According to figures compiled by the Earth
Policy Institute, world grain consumption has exceeded global
production in six of the last seven years, falling over 60 million
tonnes below consumption in 2006. Global grain reserves have
fallen to 57 days from a high of 130 days in 1986. After keeping
pace with population growth from 1960 until the late 1980s, per capita
grain production has shown a distinct flattening and declining trend in
the last 20 years.
At
its heart the "Green Revolution" is yet another example of the enormous
usefulness of oil. Without large quantities of cheap oil, this
revolution could not have occurred. The simple
fact published in a University
of Michigan study in 2000 that every calorie of food energy
consumed in the United States embodies over seven calories of non-food
energy (and other studies that have placed the ratio at 10:1) make the
linkage clear. The United States currently uses over 12% of its
total oil consumption for the production and distribution of
food. As the oil supply begins its inevitable
decline, food production will be affected. While it is probable
that most nations will preferentially allocate oil and natural gas
resources to agriculture by one means or another, it is inevitable that
over the next decades the food supply key to maintaining our burgeoning
population will come under increasing pressure, and will be subject to
its own inescapable decline.

Carrying
Capacity: Conclusion

Oil
and
its companion natural gas together make up about 60% of humanity's
primary energy. In addition, the energy of oil has been leveraged
through its use in the extraction and transport of coal as well as the
construction and maintenance of hydro and nuclear generating
facilities. Oil is as the heart of humanity's enormous energy
economy as well as at the heart of its food supply. The following
conclusion seems reasonable:

Humanity's use
of oil has quadrupled
the Earth's carrying capacity since 1900.

Overshoot

In
ecology,
overshoot is said to have occurred
when a population's consumption exceeds the carrying capacity of its
environment, as illustrated in this graphic:

When a
population rises beyond the carrying capacity of its environment, or
conversely the carrying capacity of the environment falls, the
existing population cannot be supported and must decline to match the
carrying capacity. A population cannot stay in overshoot for
long. The rapidity, extent and other characteristics of the
decline depend
on the degree of overshoot and whether the carrying capacity continues
to be eroded during the decline, as shown in the figure above.
William Catton's book "Overshoot" is recommended for a full treatment
of the subject.

There are two ways a population can regain a balance with the carrying
capacity of its environment. If the population stays constant or
continues to rise, per capita consumption must fall. If per
capita consumption stays constant, population numbers must
decline. Where the balance is struck between these endpoints
depends on how close the population is to a subsistence level of
consumption. Those portions of the population that are operating
close to subsistence will experience a reduction in numbers, while
those portions of the population that have more than they need will
experience a reduction in their level of consumption, but without a
corresponding reduction in numbers. Populations
in
serious overshoot always decline. This
is seen
in wine vats when the yeast cells die after consuming all the sugar
from the grapes and bathing themselves in their own poisonous alcoholic
wastes. It's seen in predator-prey relations in the
animal world, where the depletion of the prey species results in a
die-back of the predators.
Actually, it's a bit worse than that. The
population may actually
fall to a lower level than was sustainable before the overshoot.
The reason is that unsustainable consumption while in overshoot allowed
the species to use more non-renewable resources and to further poison
their environment with
excessive wastes. It is a common understanding of ecology that
overshoot degrades the carrying capacity of the environment (as
illustrated in the declining "Carrying Capacity" curve in the above
figure). In
the case of humanity, our use of oil has allowed us to perform
prodigious feats of resource extraction and waste production that would
simply have been inconceivable before the oil age. If our oil
supply declined, the lower available energy might be insufficient to
let
us extract and use the lower grade resources that remain. A
similar case can be made for a lessened ability to deal with wastes
in our environment

It
is
important to
recognize that humanity is not, overall, in a position of overshoot at
the moment. Our numbers are still growing (though the rate
of growth is declining). However, we are getting
obvious signals from our environment that all is not well. These
signals seem to be telling us we are approaching the maximum carrying
capacity. If the carrying capacity were to be reduced as our
numbers continued to grow we could find ourselves in overshoot rather
suddenly. The consequences of that would be quite grave.

An Image of
Overshoot

The
predicament of a population entering overshoot is illustrated by a
short scene from the
children's cartoon series about Wile E. Coyote and the Road Runner.

As the scene opens, our hero, Wile E. Coyote, is zooming hungrily
across the top of a mesa, propelled by the exuberant blast of his new
Acme Rocket Roller Skates. Suddenly a sign flashes into
view. It reads, "Danger: Cliff Ahead." The coyote tries
desperately to change course, but his speed is too great and rocket
roller skates are hard to control at the best of times. Just
before the edge of the cliff the rocket fuel that was sustaining his
incredible velocity
runs out; the engines of his roller skates die with a little puff of
smoke. The coyote begins to slow but it's too late, his inertia
propels him onward. Suddenly the ground that moments before had
ample capacity to carry him
in his headlong flight falls away beneath him. As he overshoots the edge high above the
canyon floor, he experiences a horrified moment of dawning realization
before nature's impersonal forces take over.

The Role of Peak Oil

As we
all
know but are sometimes reluctant to contemplate, oil
is a finite, non-renewable resource. This automatically means
that its use is not sustainable. If
the use of oil is not sustainable, then of course the added carrying
capacity the oil has provided is likewise unsustainable. Carrying
capacity has been added to the world in direct proportion to
the use of oil, and the disturbing implication is that if our oil
supply declines, the carrying capacity of the world will automatically
fall with it.

These two
observations (that oil has expanded the world's carrying
capacity and oil use is unsustainable) combine to yield a further
implication. While humanity has apparently not yet reached the
carrying capacity of a world with
oil, we are already in drastic
overshoot
when you consider
a world without oil. In fact our
population today is at least five times what it was before oil came on
the scene, and it is still growing. If
this sustaining resource were to be exhausted, our population would
have no option but to decline to the level supportable by the world's
lowered carrying capacity.

What are the chances that we will experience a decline in our global
oil supply? Of course given that oil is a finite, non-renewable
resource, such an occurrence is inevitable. The field of study
known as Peak Oil has generated a vast amount of analysis that
indicates this decline will happen soon, and may even be upon us right
now.

Individual oil fields tend to show a more or less bell-shaped curve of
production rates - rising, peaking and then falling. Once a field
has entered decline it has been found that no amount of remedial
drilling or new technology will raise its output back to the
peak rate. The theory of Peak Oil says that the world's oil
production
can be modeled as a single, enormous oil field, and will therefore
exhibit this same production curve. It is intuitive that if all the oil
fields in the world enter decline, and insufficient replacement fields
can be found
and developed, the world's production will decline.

The signals of Peak Oil are all around for those who know what to look
for: the continuing two-year-old plateau in the world's conventional
crude oil production; the crash of Mexico's giant Cantarell oil field
last year; the U.K. slipping from being an oil exporting nation to a
net importer in 2005; the fact that three of the world's four largest
oil fields are confirmed to be in decline; the analysis on The Oil Drum of Saudi
Arabia's super-giant Ghawar field that indicates it may be teetering on
the
brink of a crash; the fact that over two thirds of the world's oil
producing nations are experiencing declining production; delays and
cost overruns in new projects in the Middle East, Kazakhstan and
Canada's tar sands. To make matters worse, according to
several analyses including a
very thorough one done by a PhD candidate in Sweden, the addition
of new projects is unlikely to delay the terminal decline by more than
a few
years.

Understanding
the role of oil in expanding the earth's carrying
capacity brings a new urgency to the topic of Peak Oil. The
decline in oil supply will reduce the planet's carrying capacity, thus
forcing humanity into overshoot with the inevitable consequence of a
population decline. The date of the peak will mark the point at
which we should expect to see the first effects of overshoot. The
rapidity of the decline following the peak will determine whether our
descent will be a leisurely stroll down to the canyon floor or a
headlong tumble carrying a little sign reading, "Help!"

Time
Frame and Severity

The
first
questions everyone one asks when they accept the concept of Peak Oil
is, "When is it
going to happen?" and "How fast is the decline going to be?" Peak
Oil predictions are hampered by the lack of data transparency by many
oil producers. They are reluctant to publish verifiable reserve
figures, field-by-field production numbers, or observations of the
performance of individual oil fields. As
a result the fully correct answer to both questions is, "We don't know
yet." This isn't the whole answer, though. As with many
predictions we
can specify probable ranges based on the current evidence, observed
trends over the last few years and published future development and
production plans. The guesses are becoming more and more educated as
time goes by.

Several "heavy hitters" in the Peak Oil field have said the peak has
already happened. These include Dr. Kenneth Deffeyes (a colleague
of
Dr. M. King Hubbert), major energy investor T. Boone Pickens, energy
investment banker Matthew Simmons (who first sounded the alarm about
Saudi Arabia's impending depletion) and Samsam Bakhtiari, a
retired senior
expert with the National Iranian Oil Company.

The steepness of the post-peak decline is open to more debate than the
timing of the peak itself. There seems to be general agreement
that
the decline will start off very slowly, and will increase gradually as
more and more oil fields enter decline and fewer replacement fields are
brought on line. The decline will eventually flatten out, due
both to
the difficulty of extracting the last oil from a field as well as the
reduction in demand brought about by high prices and economic slowdown.

The post-peak decline rate could be flattened out if we discover new
oil to replace the oil we're using. Unfortunately our consumption
is outpacing our new discoveries by a rate of 5 to 1. to make
matters worse, it appears that we have probably already discovered
about 95% of all the conventional crude oil on the planet.

A full picture of the oil age is given in the graph below. This
model
incorporates actual production figures up to 2005 and my best estimate
of a reasonable shape for the decline curve. It also incorporates
my
belief that the peak is happening as we speak.

Maintaining
Our Carrying Capacity

The
consequences of overshoot might be avoided if we could find a way to
maintain the Earth's carrying capacity as the oil goes away. To
assess the probability of this, we need to examine the various roles
oil plays in maintaining the carrying capacity and determine if there
are available substitutes with the power to replace it in those
roles. The critical roles oil and its companion natural gas play
in our society include transportation, food production, space heating
and industrial production of such things as plastics, synthetic fabrics
and pharmaceuticals. Of these the first three are critical to
maintaining human life.

Transportation

Peak
Oil
is fundamentally a liquid fuels crisis. We use
70% of the oil for transportation. Over 97% of all transportation
depends on oil. Full substitutes for oil in this area are
unlikely (I'd go so far as to say impossible). Biofuels are extremely
problematic: their net energy is low, their production rates are
also low, their environmental costs in soil fertility are too
great. Crop based biofuels compete directly with food, while
cellulosic technologies risk "strip mining the topsoil" at the
production
rates needed to offset the loss of oil. Electricity will be able
to substitute in some applications such as trains, streetcars and
perhaps
battery powered personal vehicles, though at significant cost in terms
of both flexibility and economics. There is no realistic
substitute for jet fuel.

Food

Oil
is
used in tilling, planting, weeding, harvesting and transporting food,
as well as in pumping water for crop irrigation. Natural gas is
used to make the vast quantities of fertilizer required to support our
industrial, monoculture agribusiness system. As oil and natural
gas decline, global food output will fall. This will be offset to
some degree by the adoption of more effective and less
resource-intensive farming practices. However, it is not clear
that such practices could maintain the enormous food production
required, especially as much of the world's farmland has been decimated
by long term monocropping and will require fertility remediation to
produce adequate crops without fertilizer inputs.

Heat

In
northern climates the fuel of choice for building heat is natural
gas. Gas is on its own imminent "peak and decline" trajectory,
made worse by the fact that it is harder to transport around the world
than oil. The only realistic replacement for natural gas is
electric heat. It is quite possible that the rapid adoption of
electric resistance heating in cold climates could lead to a
destabilization of
under-maintained and over-used distribution grids, as well as localized
shortages of generating capacity. While there are technologies
that will allow us to increase the generation of electricity, they all
have associated problems - coal produces greenhouse gases, nuclear
power produces radioactive waste and is politically unpalatable in many
countries and solar photovoltaic is still too expensive. Wind
power is showing promise, but is still hampered by issues of scale and
power variability.

I think that we will strive mightily to produce alternative energy
sources to maintain the carrying capacity, but I am convinced we will
ultimately fail. This is due to issues of scale (no alternatives we
have come up with so far come within an order of magnitude of the
energy required), issues of utility (oil is so multi-talented that it
would take a large number of products and processes to fully replace
it), issues of unintended consequences (as is currently being
recognized with biofuels) and issues of human behaviour (a lack of
international cooperation is predicted by The Prisoner’s Dilemma, and
behaviours such comfort-seeking, competition for personal advantage and
a hyperbolic
discount function are planted deep in the human genome as explained in
Reg Morrison’s “The Spirit in the Gene” and in my article on
Hyperbolic Discount Functions).
We will be able to replace some small portion of
the carrying capacity provided by oil, but in the absence of oil it is
not clear how long such alternatives will remain available, relying as
they do on highly technical infrastructure that currently runs on oil
like everything else.

Implications

Given
the
fact that our world's carrying capacity is supported by oil, and that
the oil is about to start going away. it seems
that a population decline is inevitable. The form it will take,
the factors that will precipitate it and the widely differing regional
effects are all imponderables. Some questions that we might be
able to answer (though with a great degree of uncertainty) are "When
will it start?", "When will it end?", "How much control
will we have?", "How bad will
it be?" and "How many people will be left?" The rest of this
article is devoted to a high-level population model that attempts to
address these questions.

A Simple Model of
Population Decline

Parameters

To
set
the parameters of our model, we need to answer the four questions I
posed above.

When Will The Decline Start?

This depends entirely on the timing of Peak
Oil. My
conclusion that the peak is occurring now makes it easy to pick a start
date. The model starts this year, though a start date five or ten
years from now would not affect the overall picture.

When Will it End?

Given that oil is a primary determinant of carrying
capacity,
the
obvious answer is that the situation will stabilize when the
oil is gone. The oil will never be completelygone of
course, so we
can modify
that to read, "When oil is unavailable to most of humanity." We
know that point will come, because oil is a finite, non-renewable
resource, but when will that be?

Based on the model in the figure above I chose an end date of
2082, 75 years from now.

How Much Control Will We Have?

Will we be able to mitigate the population decline rate
through
voluntary
actions such as reducing global fertility rates, and making the oil
substitutions I mentioned above.

I have decided (perhaps arbitrarily) that the oil substitutions would
not affect the course of the decline, but would be used to determine
the sustainable number of people at the end of the simulation.

Fertility rates are an important consideration. The approach I've
taken is to model the net birth rate, the
combination of natural fertility and death rates that give us our
current global population growth of 75 million per year. I
modified that by having it decline by 0.015% per year. This
reflects both a declining fertility rate due to environmental factors
and some degree of women's education and empowerment, as well as a
rising death rate due to a decline in the the global economy. I
do not
think that traditional humane models such as the Benign Demographic
Transition
theory will be able to influence events, given that the required
economic growth is likely to be unavailable.

How Bad Will It Be?

This question comes from the assumption that the
decline in
net
births alone will not be enough to solve the problem (and the
simulation bears this out). This means that some level of excess
deaths will result from a wide variety of circumstances. I
postulate a rate of excess deaths that starts off quite low, rises over
the decades to some maximum and then declines. The rise is driven
by the worsening global situation as the overshoot takes effect, and
the subsequent fall is due to human numbers and activities gradually
coming back into balance with the resources available.

How Many People Will Be Left?

Taking the carrying
capacity effects discussed above into account, I initially set the bar
for a sustainable
population at the population when we discovered oil in about 1850. This
was about 1.2 billion people. Next I subtracted some number to
account for the world's degraded carrying capacity, then added back a
bit to
account for our increased knowledge and the ameliorating effects of oil
substitutes. This is a necessarily imprecise
calculation, but I have settled on a round number of one
billion people as the
long-term
sustainable population of the planet in the absence of oil.

Comments

The
model
is a simple arithmetical simulation that answers the following
question: "Given the assumptions about birth and death rates
listed above, how will human population numbers evolve to get
from our current population of 6.6 billion to a sustainable population
of 1 billion in 75 years?" It is not a predictive model. It
is aggregated to a global level, and so can tell us nothing about
regional effects. It also cannot address social outcomes.
Its primary intent is to allow us to examine the roll that excess
deaths will play in the next 75 years

The Model

We
will
start by graphing the net birth rate over
the period 2007 to 2082, incorporating a 0.015% annual decline:
As you can see, the net birth rate declines to zero by 2082.

Is it possible that this declining birth rate will get us
closer
to our sustainable population goal of one billion?
The following graph shows our population growth with the
effects of the declining net birth rate shown above:

As you can see, my assumption about declining birth rates
leads
to a stable population, but it's still 50% larger than today. In fact,
this projection is remarkably similar to the one produced by the United
Nations, which estimates a global population of 9.2 billion in
2050. The message of this graph is clear. If we need to reduce
our
population, simply adjusting the birth rate is insufficient.
There will be excess deaths required to reach our target.

The following graph shows the excess death rate rising and then falling
as described above. I will reiterate that the origin of these
excess deaths is not considered in the model. It is sufficient to
understand that these are not the result of old age or the various
"natural causes" we have come to accept as a part of our modern
life. These deaths may be due to such things as rising infant
mortality rates, shorter adult life expectancies, famine, pandemics,
wars etc. Some of these
deaths will be from human agency, but most will not.

Applying the above excess death rate to our current
population
yields
the following curve. As you can see, the number
of excess deaths per year increases
quite rapidly (consistent with the effects of overshoot) and then falls
off as the population comes back into balance with the resources
available. The peak rate of deaths comes much earlier than the
peak in the percentage death rate shown in the above graph because the
population starts to decline rapidly. A lower percentage death
rate acts on a larger population to produce a higher numerical death
rate. As the population declines so does the numerical death
rate, even when the percentage rate still increasing.

The final graph is the outcome of the full simulation.
It
starts from our current population and shows the combined effects of a
declining net birth rate and the excess death rate due to falling
carrying capacity as described above. The goal of
the model has been met: it has achieved a
sustainable world
population of one billion by the year 2082.

The Cost

The human cost of such an involuntary population rebalancing
is,
of
course, horrific. Based on this model we
would experience an average excess death rate of 100 million per year
every
year for the next 75 years to achieve our target population of one
billion by
2082.
The peak excess death rate would happen in about 20 years, and would be
about 200 million that year. To put this in perspective, WWII
caused an excess death rate of only 10 million per year for only six
years.

Given
this, it's not hard to see why population control is the untouchable
elephant in the room - the problem we're in is simply too big for
humane or even rational solutions. It's also not hard to see why some
people are beginning to grasp the inevitability of a human die-off.

Conclusion

One
of the common accusations leveled at those who present
analyses like this is that by doing so they are advocating or hoping
for the
massive population reductions they describe, and are encouraging
draconian and inhumane measures to achieve them. Nothing could
be further from the truth. I am personally quite attached
to the world
I've grown up in and the people that inhabit it, as is every other
population commentator I am familiar with. However, in my
ecological and Peak Oil
research over the last several years I have begun to see the shape of a
looming catastrophe that has absolutely nothing to do with human
intentions, good or ill. It is the simple product of our species'
continuing growth in both numbers and ability, an exponential growth
that
is taking
place within the finite ecological niche of the entire world.
Our recent effusive growth has been fueled by the draw-down of
primordial stocks of petroleum which are about to deplete while our
numbers and activities continue to grow. This is a simple,
obvious recipe for disaster.

This model is intended to give some clarity to that premonition of
trouble. It carries no judgment about what ought to be, it
merely describes what might be. The model is
likewise no crystal ball. It offers no predictions and no
insights into the
details of what
will happen. It presents the simple arithmetic consequences of
one set
of
assumptions, albeit assumptions that I personally feel have a
reasonable probability of being fulfilled.

There are factors .that will affect the course of events that have not
been considered in the model. Readers may legitimately take me to
task for not considering or summarily dismissing the various ways
humanity is already trying to alleviate some of the foreseen
dangers. For instance, my model does not mention global warming
or carbon caps, and dismisses most alternative energy sources as
ineffective. The model also does not address the regional
differences that are bound to expand as the crisis unfolds. While
such criticisms are justified and are well worth exploring in the
context of oil decline, the purpose of this article is to take a
high-level look at the global population situation, considering
the entire planet as one ecological niche with a single aggregate
carrying capacity supported by oil in its role as a facilitator of
transportation and food production.

The model warns us that the
involuntary decline of the human population in the aftermath of the Oil
Age will
not happen without overwhelming universal hardship. There are
things we will be able to do as individuals to minimize the personal
effects of such a decline, and we should all be deciding what those
things need to be. It's never too early to prepare for a storm
this big.

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